Synthesis of silver halide nanocomposites templated by amphiphilic graft copolymer and their use as olefin carrier for facilitated transport membranes

A novel amphiphilic comb-like copolymer consisting of poly(vinyl chloride) (PVC) main chains and poly(4-vinyl pyridine) (P4VP) side chains, i.e. PVC-g-P4VP with 65:35 wt% is synthesized via atom transfer radical polymerization (ATRP). This self-assembled copolymer is used to template the growth of silver bromide (AgBr) nanoparticles with diameters of 10-50 nm, as characterized by UV-vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Upon introduction of ionic liquid, i.e. 1-methyl-3-octylimidazolium nitrate (MOIM⁺NO₃^-), the surface of AgBr nanoparticles is more partially positively charged due to the interactions between NO₃^- ions and the surfaces of nanoparticles, as revealed by FT-Raman and X-ray photon spectroscopy (XPS). We also demonstrate the ability of AgBr as a new type of olefin carrier by tuning the interactions of positively charged AgBr with the C{double bond, long}C bond of olefin molecules. As a result, the membranes containing AgBr nanocomposites exhibit highly stable separation performances for propylene/propane mixture, i.e. a mixed gas selectivity of 6 and a permeance of 5.7 GPU.